/*
 * @Description:String 包装器类型
 * @Author: admin
 * @Date: 2021-06-08 11:31:45
 * @LastEditors: admin
 * @LastEditTime: 2021-06-08 11:47:57
 */

// var s1 = "hello,"
// var s2 = "world!"
// var s4 = "hello，briup!"
// var s3 = s1.concat(s2, s4);
// console.log(s3);
// console.log(s1 + s2 + s4);

var s = "Hello,Word!"
// console.log(s.slice(3, 7));;//lo,w
// console.log(s);
// console.log(s.substr(3, 7));;//lo,word
// console.log(s);
// console.log(s.substring(3, 7));;//lo,w
// console.log(s);
// var a = "   1 2 3   ";
// console.log(a.trim());
console.log(s);
console.log(s.toUpperCase());
console.log(s.toLowerCase());